DE102018124922B4 - Diesel hybrid drive technology with urea-free NOx conversion - Google Patents

Abstract

Drive device for a vehicle with a diesel engine (11) and an electric motor (12), the drive device (10) comprising: - an exhaust gas aftertreatment device (13) for treating the exhaust gas (34) of the diesel engine (11), the exhaust gas - Aftertreatment device (13) has an exhaust gas passage (14) on which are arranged in the flow direction of the exhaust gas (34): ◯ a controllable fuel addition device (17) to add fuel to the exhaust gas (34) in the exhaust gas passage (14); ◯ A catalytic converter (20) for removing nitrogen oxides (NOx) from the exhaust gas (34) by reaction with the added fuel; - A control device (23) for controlling the addition of fuel; characterized in that the control device (23) is designed for this purpose - In high-load operation (MODE 1) of the drive device (10) to control the fuel addition device (17) in such a way that the air-fuel is added by adding fuel to the exhaust gas (34) (post-engine addition quantity) Ratio of the A bgases (34) in the area of the catalytic converter (20) is approached to a target value which is close to the stoichiometric equilibrium; AND- to determine a required amount for a fuel addition in the diesel engine (11) (in-engine addition amount), which is required in addition to the after-engine addition amount to keep the air-fuel ratio of the exhaust gas (34) in the range of the catalytic converter (20) to approach the target value; AND - to generate an addition control instruction for the diesel engine (11) so that the in-engine addition amount of fuel is added to the drive device (10) in high-load operation (MODE 1); - a compensation control instruction for the electric motor (12 ) to generate so that an excess power (Pex) of the diesel engine (11), which results from the in-engine addition amount, is absorbed by the electric motor (34).

Description

The present invention relates to a drive technology for hybrid diesel vehicles, in particular for passenger vehicles or trucks, which have a diesel engine and an electric motor as travel drives which can be operated in combination.

In practice it is known to equip diesel engines with an exhaust gas aftertreatment device to reduce the nitrogen oxides by adding a separate reducing agent in a catalytic converter for selective catalysis. The reducing agent is usually ammonia, which is formed when injected urea breaks down in the exhaust gas passage. But it is also possible to add ammonia directly as a reducing agent. The catalytic converter is usually an SCR catalytic converter.

On the other hand, it is known to additionally combine a diesel engine with an electric motor in order to save fuel and combustion emissions in order to create a hybrid drive. With a hybrid drive, load distribution between the diesel engine and the electric motor is made possible. The electric motor can generate propulsive power by drawing electrical energy from an electrical driving energy store, as well as absorbing mechanical power with recuperation (charging) of the driving energy store, which can come from the diesel engine and / or from the dynamics of the vehicle.

For example, in Scripture DE 10 2016 115 135 A1 discloses a method for reducing NOx emissions from an engine.

Compared to other internal combustion engines, such as gasoline engines, diesel engines have significantly higher production costs, but they offer significantly lower CO2 emissions and, per se, have lower fuel consumption. It has been shown that a drive device that combines a diesel engine, an electric motor and an SCR catalyst operated with urea or ammonia entails such high manufacturing costs that this type of drive is not accepted by the customer.

The object of the present invention is to provide an improved drive technology for a vehicle with a diesel engine and an electric motor, which in particular has lower manufacturing costs and can comply with the strict emission guidelines for CO2 and nitrogen oxide emissions. The drive technology comprises a drive device and an operating method for the drive device. The invention solves the problem by the characterizing features of the independent claims.

The drive device according to the present disclosure can be used with a diesel hybrid drive, i. with a combination of a diesel engine and an electric motor of the above Kind be combined. Alternatively, the drive device itself can comprise the diesel engine and / or the electric motor and any associated control components thereof.

A first aspect of the disclosure is explained below, which alone or in combination with further aspects, which are explained below, contributes to solving the problem.

The drive device according to the present disclosure includes an exhaust gas aftertreatment device for treating the exhaust gas of the diesel engine. The exhaust gas aftertreatment device has an exhaust gas passage on or in which a controllable fuel addition device and a catalytic converter are arranged along the flow direction of the exhaust gas. The fuel adding device is provided and designed to add a fuel to the exhaust gas in the exhaust gas passage. This can in particular be the (diesel) fuel that is also used to operate the diesel engine. In other words, the exhaust gas aftertreatment device is designed to carry out a post-engine injection.

The catalyst of the exhaust gas aftertreatment device according to the present disclosure is provided and designed for removing nitrogen oxides (NOx) from the exhaust gas, to be precise by converting the nitrogen oxides using the added fuel. In addition, the catalytic converter can be designed to store or adsorb nitrogen oxides.

The exhaust gas aftertreatment device further comprises a control device for controlling the addition of fuel.

The fuel is preferably added not only as a post-engine injection but also via an in-engine injection.

The addition of fuel to the exhaust gas takes place in such a way that the air-fuel ratio of the exhaust gas, and in particular in the area of the catalytic converter, approaches a setpoint value that is close to the stoichiometric equilibrium. The air-fuel ratio is thus changed in a region downstream of the combustion chamber in such a way that an excess of oxygen in the exhaust gas is reduced or reduced to zero. A different and significantly higher air-fuel ratio can be present inside the combustion chamber, in particular before and during the combustion.

The air-fuel ratio is also known as the lambda value. For the combustion process in a diesel engine - especially in the high-load operation with a conventional diesel fuel explained below - a lambda value must be provided before or during the ignition of the air-fuel mixture in the combustion chamber that is significantly above 1, i.e., for example Has a value of 1.3 or higher. If the lambda value before or during the combustion of conventional diesel fuel is in the range of the stoichiometric equilibrium, i.e. Lambda is equal to 1 or lambda in the range from 1.05 to, for example, 1.1 or 1.15, an inadmissible amount of soot is produced during combustion.

In the case of gasoline engines, on the other hand, it is possible to provide an air-fuel mixture close to the stoichiometric equilibrium without excessive generation of soot. Lambda is equal to or less than 1.0. In gasoline engines, it is therefore possible to carry out an efficient nitrogen oxide reduction with a particularly simple and inexpensive three-way catalytic converter.

In conventional diesel engines, the excess oxygen in the exhaust gas means that the three-way catalytic converter cannot be used because it only works in a narrow lambda value range around lambda = 1.0.

In the context of the present invention, a new operating mode is provided for a diesel hybrid drive or for the drive device according to the disclosure, which is referred to as high-load operation.

In high-load operation, the above-mentioned post-engine injection, in which a certain post-engine added amount of fuel is added to the exhaust gas, changes the air-fuel ratio for the exhaust gas (at least) downstream of the engine outlet and the approximated stoichiometric equilibrium. This makes it possible to dispense with expensive selective catalysis and the associated urea or ammonia injection.

In addition, it is provided that, in high-load operation, an amount required for adding fuel to the diesel engine is determined as an in-engine adding amount. The in-engine addition amount can be required at least temporarily in addition to the after-engine addition amount in order to enable the lambda value to approach the stoichiometric equilibrium. In particular, the precisely controllable fuel injectors, which are generally provided on the diesel engine anyway, allow additional fuel to be added particularly precisely with regard to the injection quantity and with regard to the injection timing. Thus, for example, the in-engine added amount can be used to achieve a fine approximation of the air-fuel ratio in the exhaust gas to the target value, while the post-engine added amount provides a rough approximation.

The post-engine fuel addition can preferably be controlled by a pilot control, while the in-engine fuel addition can take place by a regulation.

The amount to be added in the engine can be determined in any way and by any device or method, preferably by the control device of the drive device and further preferably by a target / actual comparison, i.e. a comparison of the actual air-fuel ratio of the exhaust gas (actual value) with a target value. The actual air-fuel ratio of the exhaust gas is preferably determined in a region downstream of the post-engine fuel addition, in particular by a lambda sensor.

The control device of the exhaust gas aftertreatment device preferably also generates an addition control instruction for the diesel engine so that the in-engine addition amount of fuel is added to or in the diesel engine in high-load operation.

To determine the in-engine added amount, in particular an actual lambda value or an actual air-fuel ratio in the exhaust gas downstream of the after-engine fuel addition can be measured by a lambda sensor, which is preferably arranged in the vicinity of the catalytic converter is, in particular in the entrance area of the catalytic converter or in the flow direction of the exhaust gas between the fuel addition device and the catalytic converter.

The in-engine addition amount can be calculated on the basis of a determined (residual) deviation between the target value and the actual air-fuel ratio of the exhaust gas.

The amount added after the engine is preferably greater and, in particular, significantly greater than the amount added in the engine.

The additional fuel that is injected by adding fuel to the engine can generate excess power that exceeds the regular power requirement that has been determined, for example, according to the accelerator pedal position of the vehicle or according to another load request. Such excess power from the diesel engine could result in unexpected driving behavior.

It is known to those skilled in the art that excessive operation of a motor can be characterized by various parameters that can be used in particular individually or in combination. It is also known to those skilled in the art that parameters with different time relationships can be used to characterize the operation of an engine, i. For example, momentary parameters, short-term parameters and duration parameters. In the context of the present disclosure, the term “performance” is intended to apply as a generic term for these various parameters. It thus includes both a “mechanical performance” and a “mechanical work” or “torque”. The term performance is used to represent the various possible parameters. The term “torque” is also used. Those skilled in the art are familiar with the physical phenomena that can occur when operating a diesel engine and an electric motor in a hybrid system. He knows that the torque of an internal combustion engine depends essentially on the amount of fuel burned, which is why the torque is a particularly frequently used parameter. He is also aware that the same performance can be achieved through different combinations of speed and torque, and that conversion can be carried out under the various possible parameters that are summarized under the term “performance”.

In the context of the present disclosure, it is provided that a compensation control instruction is generated for the electric motor so that the excess power resulting from the in-motor added amount or the corresponding excess torque of the diesel engine is absorbed by the electric motor. The excess power can in particular be used to charge the drive energy storage device and / or to operate electrical consumers on the vehicle.

The combination of the fuel additions after the engine and in the engine enables a particularly precise adjustment of the air-fuel ratio in the exhaust gas in the area of the catalytic converter, in particular through the combination of a somewhat coarser pilot control with a fine control.

Thus, a catalytic converter can also be used for the diesel hybrid drive which does not need to have any selective catalytic properties; in particular, a so-called nitrogen oxide storage catalytic converter (LNT) or (exclusively) a three-way catalytic converter can be used. As an alternative or in addition, it is possible to use a combination of a nitrogen oxide storage catalytic converter (LNT) and a three-way catalytic converter. Again, as an alternative or in addition, a catalytic converter for selective catalysis of nitrogen oxides (SCR) can be used, which is operated without urea or ammonia injection. In other words, it is sufficient that the drive device only has one or more catalytic converters that remove nitrogen oxides from the exhaust gas (exclusively) by reacting with the added fuel. It is therefore not necessary to add a separate reducing agent that is not a fuel.

The disclosed drive technology comprises, as a further aspect, which can be used alone or in combination with the aforementioned aspect, an operating method in which high-load operation is provided as one of various operating modes.

Particular advantages for an efficient and / or low-emission use of drive technology result when the high-load operating mode is dependent on a nitrogen oxide conversion efficiency and in particular dependent on an exhaust gas temperature and also dependent on a state of the Hybrid system is selected, ie the instantaneous availability of drive support from the electric motor or the instantaneous possibility of charging the driving energy store. Other operating modes can be adapted in such a way that, on the one hand, a particularly efficient nitrogen oxide conversion takes place and, on the other hand, the particular advantages of the diesel engine, namely the low CO2 emissions, are used.

The adaptation of the other operating modes has the particular advantage that the high-load operating mode is only used in a very small proportion of the driving time, for example in less than 3% or less than 1% of the driving time. In this way, the additional consumption of fuel that is generated during high-load operation by adding fuel to the exhaust gas is reduced to a minimum overall and compensated for by the advantages of the hybrid drive.

Further advantageous developments of the invention are specified in the subclaims.

• 1: eine schematische Darstellung der Antriebsvorrichtung gemäß der vorliegenden Offenbarung;
• 2: ein Schemadiagramm zur Erläuterung der Entstehung von Stickoxidmengen an einem Dieselmotor bei unterschiedlichen Betriebsbedingungen;
• 3: ein Ablaufdiagramm zur Erläuterung verschiedener Aspekte eines Betriebsverfahrens gemäß der vorliegenden Offenbarung.

The invention is shown schematically and by way of example in the drawings. These show:

• 1 : a schematic representation of the drive device according to the present disclosure;
• 2 : a schematic diagram to explain the generation of nitrogen oxide quantities in a diesel engine under different operating conditions;
• 3 FIG. 12 is a flow chart for explaining various aspects of an operating method according to the present disclosure.

1 shows a drive device ( 10 ) in a schematic representation. The drive device ( 10 ) is intended and designed for use on a vehicle (not shown). The vehicle can be powered by a diesel engine ( 11 ) and an electric motor ( 12 ) feature. The diesel engine ( 11 ) is for simplified representation by a combustion chamber ( 27 ) represents. Intake air is taken from an intake passage ( 24 ) through an inlet valve into the combustion chamber ( 27 ) and burned there with a fuel that is injected through a fuel injector ( 28 ) is injected. The fuel injector ( 28 ) is preferably on or in the combustion chamber ( 27 ) arranged.

The intake air can be supplied by at least one compressor ( 19th ) to be charged. The compressor is in the intake passage upstream of the engine inlet ( 25th ) and downstream to a fresh air inlet ( 26th ) arranged. It is preferred directly through a turbine ( 18th ) driven in the exhaust gas passage ( 14th ) is arranged.

For the energy supply of the electric motor ( 12 ) an electric driving energy storage ( 29 ) be provided.

The diesel engine ( 11 ) and / or the electric motor ( 12 ) as well as the aforementioned additional components can each be part of the drive device individually or in any combination ( 10 ) in accordance with the present disclosure.

The drive device ( 10 ) includes an exhaust aftertreatment device ( 13 ). This has an exhaust passage ( 14th ), which extends from an engine outlet ( 15th ) towards an exhaust ( 16 ) extends and one of the diesel engine ( 11 ) escaping exhaust gas leads. The direction of flow of the exhaust gas ( 34 ) is accordingly of the engine exhaust ( 15th ) to the exhaust ( 16 ) directed towards.

In the specified flow direction of the exhaust gas ( 34 ) are on or in the exhaust gas passage ( 14th ) at least one controllable fuel dispenser ( 17th ) and a catalyst ( 20th ) arranged, which have the above training.

An operating method according to the present disclosure provides for operating the aforementioned drive device, wherein the operating method can comprise a plurality of operating modes, including at least one high-load operating mode (MODE 1) in which the steps mentioned below are carried out.

Fuel is in the exhaust ( 34 ) downstream of the diesel engine (1) and upstream to the catalytic converter ( 20th ) is injected as a post-engine fuel additive to improve the air-fuel ratio of the exhaust gas ( 34 ) in the area of the catalytic converter ( 20th ) to approximate a target value that is close to or equal to the stoichiometric equilibrium, ie lambda is equal to 1. A required quantity for a (additional) fuel addition in the diesel engine ( 11 ), which is referred to below as the in-motor added amount. In the- Engine added quantity may be necessary in order to add more fuel to the diesel engine in addition to the post-engine fuel mentioned above ( 11 ) and thereby the air-fuel ratio of the exhaust gas ( 34 ) in the area of the catalytic converter ( 20th ) to approximate the aforementioned target value.

According to a preferred embodiment, the post-engine fuel added amount is significantly greater than the in-engine added amount. In particular, the amount added after the engine can reduce the substantial or predominant part of an excess of oxygen in the exhaust gas ( 34 ), which in regular operation after combustion in a combustion chamber ( 27 ) of the diesel engine ( 11 ) would exist, and thereby the air-fuel ratio of the exhaust gas ( 34 ) can be approximated to the target value. For adding fuel after the engine, the fuel adding device is preferred ( 17th , 17 ' ) operated between the engine outlet ( 15th ) and the catalytic converter ( 20th ) in at least a single version, possibly in multiple versions on or in the exhaust gas passage ( 14th ) is provided. The amount of fuel added after the engine can be selected, for example, to reduce at least 50% and preferably more than 80% of the aforementioned oxygen excess in the exhaust gas ( 34 ) to balance after regular incineration.

On or in the fuel passage ( 14th ) at least one lambda sensor ( 35 ) be provided. In particular, at least one lambda sensor ( 35 ) between the at least one fuel dispensing device ( 17th , 17 ' ) and the catalytic converter ( 20th ) arranged. Via the at least one lambda sensor ( 35 ) the air-fuel ratio of the exhaust gas ( 34 ) in front of or on the catalytic converter ( 20th ) can be recorded. Alternatively or additionally, an instantaneous air-fuel ratio of the exhaust gas ( 34 ) in front of or on the catalytic converter ( 20th ) are determined or obtained in another way, for example by calculation in a combustion model and / or by querying an external control device, for example a possibly separately provided diesel engine control device (not shown).

On the basis of the determined or obtained value for the actual air-fuel ratio of the exhaust gas ( 34 ) it can be recorded whether there is still a deviation from the target value. If this is the case, based on the determined deviation, a quantity required for adding additional fuel to the diesel engine ( 11 ) as an in-motor added amount.

The in-engine added amount is in the diesel engine ( 11 ) added. For this purpose, the control unit prefers ( 23 ) the drive device ( 10 ) generates a corresponding add-on control instruction. The control unit ( 23 ) can use a fuel injector ( 28 ) of the diesel engine directly or indirectly to carry out an in-engine fuel addition. For this purpose, the type of injection can also be specified, which is to be provided on the diesel engine for carrying out the in-engine addition quantity. The specification for the type of injection can, in particular, be part of the additional control instruction issued by the control device ( 23 ) is produced.

A specification for the type of injection can determine that the amount to be added in-motor is either to be added in full as part of a main injection or, on the one hand, proportionally as part of a main injection and, on the other hand, proportionally as part of a post-injection.

Again as an alternative, a specification for the type of injection can include that the in-motor added amount is to be added in full as part of a post-injection.

If the in-engine added amount is at least partly as part of a main injection, possibly more fuel is added to the combustion chamber ( 27 ) burned than is necessary for a power request or torque request, so that an excess power output or torque output to the diesel engine ( 11 ) he follows. The excess power or torque (Pex) of the diesel engine ( 11 ) is according to the present disclosure by the electric motor ( 12 ) by instructing it accordingly by means of a compensation control instruction. Thus, for the driver of the vehicle, the total output torque or the total output power remains in accordance with the torque request or the power request.

In the following, the term excess engine power (Pex) is used in such a way that its meaning also includes excess torque.

The selection of the high-load operating mode (Mode 1) can be made according to the in 3 shown selection process, which can be a component of the operating process according to the disclosure.

In a first step ( S10 ) a target power (P *) is determined. The target power (P *) is determined in particular on the basis of an accelerator pedal position of the vehicle and / or on the basis of a specification from an assistance system, the assistance system being, for example, a cruise control or a distance control system or a partially or fully automatic vehicle guidance method. The term setpoint power (P *) also includes a setpoint torque.

In a subsequent step ( S11 ) it is determined whether a temperature (T_Ex) of the exhaust gas ( 34 ) exceeds an upper threshold value (T2). If so (step S11 : YES), the output power or output torque (Pd) of the diesel engine ( 11 ) limited to a specified nominal continuous operation value (Pr).

The continuous operation nominal power (Pr) can be depending on a structure and any test values on the diesel engine ( 11 ) must be specified in such a way that, when the diesel engine is operated continuously with this output power (Pr), the temperature (T_Ex) of the exhaust gas maintains a specified temperature level at which no damage to the exhaust gas aftertreatment system ( 13 ) are to be expected.

The exhaust aftertreatment device ( 13 ) in particular at least one turbine ( 18th ), in particular have a high-pressure turbine, which is also preferably upstream of the catalytic converter ( 20th ) and downstream to at least one fuel addition device ( 17th ) is arranged.

Thermal damage often occurs first on the turbine blades of such a high-pressure turbine ( 18th ) so that the temperature resistance of the high-pressure turbine ( 18th ) as a measure of the permissible temperature level of the exhaust gas ( 34 ) can be used in continuous operation.

2 explains various operating conditions of a diesel engine ( 11 ) and the nitrogen oxide mass flows and exhaust gas temperatures generated, for example.

Basically, the diesel engine ( 11 ) an exhaust gas ( 34 ) at a higher temperature (T_Ex) if the in the combustion chamber ( 27 ) the amount of fuel burned (Qi) is high and / or when there are many combustion cycles, ie when the engine speed (NE) is high. However, a temperature change in the exhaust gas (T_Ex) often only takes place with a time delay to a change in the operating conditions of the diesel engine ( 11 ). An excessive increase in the exhaust gas temperature can initially lead to a reduction in the conversion efficiency or to a deterioration in the performance of a chemical reduction reaction. Raising the exhaust gas temperature even further can ultimately lead to damage or permanent impairment of the conversion efficiency.

With an increase in the combustion chamber ( 27 ) The amount of fuel burned is usually a disproportionate increase in nitrogen oxide production, ie a disproportionate increase in the NOx mass flow.

In the context of the present disclosure, it is provided that particularly high target powers (P *) are initially covered by the electric motor ( 12 ) there is electrical drive support (see step S31 in 3 ). If such electrical drive support is not possible or is no longer possible, for example because the electrical travel energy storage ( 29 ) is exhausted, the target power (P *) can only be achieved by the diesel engine ( 11 ) are generated (step S31 : NO).

If this occurs, which can happen, for example, when the vehicle is traveling uphill for a long time, the high-load operating mode (mode 1) (step S42 ) executed. In this case, the diesel engine is operated in such a way that it generates a maximum of the output power and / or the output torque (according to the regular injection control) that corresponds to the specified nominal continuous operation value (Pr). In addition, post-engine fuel addition and, if necessary, in-engine fuel addition are carried out to improve the air-fuel ratio in the exhaust gas ( 34 ) to approach the target value.

By adding fuel to the exhaust gas ( 34 ) upstream of the turbine ( 18th ) exhaust gas cooling is achieved, which can compensate for the temperature rise that may be generated by the addition of fuel in the engine. On the other hand, the catalyst ( 20th ) due to the achieved air-fuel ratio close to the stoichiometric equilibrium, very efficiently convert the nitrogen oxides (NOx) through reaction with the added fuel.

As a result of the limitation of the output power of the diesel engine, overloading of the exhaust gas aftertreatment device ( 13 ) and especially the turbine ( 18th ), even if high-load operation (mode 1) should continue for several seconds or minutes.

Since during the high-load operating mode the excess output power (Pex) of the diesel engine (1) via the electric motor ( 12 ) is recorded, the electric drive energy storage device ( 29 ) respectively.

If in step ( S31 ) it is determined that an electric drive support is still possible or possible again (step S31 : YES), the diesel engine ( 11 ) (if the exhaust gas temperature (T_Ex) is still above the threshold value (T2)) operated in such a way that it delivers power or torque (Pd) equal to or below the nominal continuous operation value (Pr). The electric motor ( 12 ) is operated in such a way that any existing performance gap between that of the diesel engine ( 11 ) output power (Pd) and the target power (P *) through the output power of the electric motor ( 12 ) is covered. This operating mode is in 3 as a step ( S33 ) provided within a hybrid operating mode (mode 2).

The operating method according to the present disclosure thus ensures that an efficient nitrogen oxide reduction is made possible in operating phases in which a high power output from the diesel engine is possible, even without the costly addition of urea or ammonia. 11 ) is required so that larger amounts of nitrogen oxides are generated, and in which, on the other hand, an electric drive support is not or no longer possible. This enables an inexpensive diesel hybrid drive technology that complies with the strict emission regulations. Possibly. The determination of the continuous operation nominal value (Pr) on the one hand and the determination of the post-engine fuel quantity on the other hand, i.e. the measures that limit or exclude an excessive increase in the exhaust gas temperature (T_Ex), can be optimized against each other depending on the specific system parameters. It is also possible to use a separate control or regulation to change the nominal continuous operation value (Pr) and / or the post-engine fuel quantity depending on the exhaust gas temperature (T_Ex) in order to enable maximum power output of the entire drive system if necessary.

The operating method according to the present disclosure also includes instructions and measures to limit or exclude insufficient nitrogen oxide conversion as a result of an exhaust gas temperature (T_Ex) that is too low. For this purpose, the operating method can in particular provide that according to step S10 first a target power or a target torque (P *) is determined. If in step S12 it is determined that the exhaust gas temperature (T_Ex) falls below a lower threshold value (T1) (step S12 : YES) can initially according to step S20 Countermeasures are taken to increase the output power of the diesel engine (Pd) and thus tend to raise the exhaust gas temperature (T_Ex). As a result, the low temperature range can be avoided in that, for example, a reduction in emissions through the use of a nitrogen oxide storage catalytic converter (LNT) is ineffective or has an insufficient degree of efficiency.

So long according to step S21 an electrical charge of the driving energy storage ( 29 ) or any other use of excess power from the diesel engine (Pd) that is above the target power (P *) is possible (step S21 : YES), the electric motor ( 12 ) operated in such a way that it absorbs the excess power or the excess torque (step S23 in 3 ).

However, if according to step S21 an electrical charge or other utilization of the excess power by the electric motor ( 12 ) is no longer possible (step S21 : NO), the diesel engine ( 11 ) deactivated so that the electric motor ( 12 ) provides the full target power or the full target torque (P *).

• - Gemäß Schritt S23 unter gleichzeitiger Ladung des Fahrenergiespeichers (29) erfolgen soll, in dem die Abgabeleistung (Pd) des Dieselmotors oberhalb der Soll-Leistung (P*) gewählt wird, und der Überschussbetrag der Leistung von dem Elektromotor aufgenommen wird; oder ob
• - die Soll-Leistung gemäß Schritt S14 vollständig durch die Abgabeleistung (Pd) des Dieselmotors erbracht werden soll; oder ob
• - eine elektrische Antriebsunterstützung gemäß Schritt S33 erfolgen soll, bei der die Soll-Leistung (P*) nur zum Teil durch die Abgabeleistung (Pd) des Dieselmotors und ergänzend durch die Abgabeleistung (Pel) des Elektromotors gedeckt wird.

In the operating method according to the present disclosure it is further provided that in operating states in which the exhaust gas temperature (T_Ex) is between the lower threshold value (T1) and the upper threshold value (T2) (step S11 : NO and step S12 : NO) a hybrid load distribution known in principle S13 is performed. The hybrid load distribution can determine essentially independently of the nitrogen oxide conversion according to optimization criteria known in practice whether the target output (P *):

• - According to step S23 with simultaneous charging of the driving energy storage ( 29 ) is to take place in which the output power (Pd) of the diesel engine is selected above the target power (P *), and the excess amount of the power is absorbed by the electric motor; or if
• - the target performance according to step S14 is to be provided entirely by the output power (Pd) of the diesel engine; or if
• - an electric drive support according to step S33 is to take place in which the target power (P *) is only partially covered by the output power (Pd) of the diesel engine and additionally by the output power (Pel) of the electric motor.

Please note that when executing according to step S33 within the general hybrid operating mode (MODE 2) there is only a limitation of the output power (Pd) of the diesel engine ( 11 ) is required if the exhaust gas temperature (T_Ex) has exceeded the second threshold value (T2). If a particularly high target power (P *) is determined only for a short period of time, but no excessive increase in exhaust gas temperature (T_Ex) can be determined (step S11 : NO), the diesel engine can step in S33 can also be operated with an output power (Pd) that is above the specified nominal continuous operation value (Pr).

As an alternative or in addition to the aforementioned features, further measures can promote the cost efficiency and the nitrogen oxide conversion efficiency of the disclosed drive technology.

Upstream of the catalyst ( 20th ) a plasma generator ( 22nd ) be arranged. A plasma generator ( 22nd , 22 ' ) can be arranged one or more times. A plasma generator is particularly preferred ( 22nd , 22 ' ) in the flow direction of the exhaust gas directly in front of, on or directly after a fuel dispenser ( 17th , 17 ' ) arranged. By the plasma generator ( 22nd ) the nitrogen oxide conversion in the catalytic converter ( 20th ) are significantly favored in cooperation with the added fuel, so that it takes place faster and / or with a greater degree of efficiency. The use of a plasma generator ( 22nd ) can take place both in high-load operation and in regeneration operation for the catalytic converter ( 20th ), which can, for example, provide for the addition of fuel outside of high-load operation.

In order to optimize the generation of nitrogen oxides in the combustion process, the drive device ( 10 ) preferably an exhaust gas recirculation device ( 30th ), the exhaust gas ( 34 ) from the exhaust passage ( 14th ) to an intake passage ( 24 ) of the diesel engine ( 11 ) returns. The exhaust gas recirculation device ( 30th ) can in particular be designed exclusively as low-pressure exhaust gas recirculation, ie it can in particular exclusively be an exhaust 34 ) return that the exhaust gas passage ( 14th ) at a point downstream of the catalyst ( 20th ) is removed. If necessary, at the exhaust passage ( 14th ) further components can be arranged which cause fuel oxidation, for example a so-called diesel oxidation catalyst (Doc). In 1 is exemplary an additional fuel oxidizer ( 21st ), which are located downstream of the catalytic converter ( 20th ) and upstream to the connection point with the exhaust gas recirculation device ( 30th ) is located. There is therefore only one exhaust gas ( 34 ) from a point of the exhaust passage ( 14th ) to which the content of free hydrocarbons in the exhaust gas ( 34 ), which result from the in-engine added amount and / or the after-engine added amount, is reduced or eliminated. Accordingly, the exhaust gas recirculation ( 30th ) no or a negligibly small amount of flammable substances for the intake passage ( 24 ) and therefore there is no compensation of the injection quantity (Qi) on the diesel engine ( 11 ) required for compensation.

On or in the exhaust gas recirculation device ( 30th ) a cooling device, in particular an exhaust gas cooler ( 31 ) be provided. The exhaust gas recirculation device ( 30th ) further preferably has a control valve ( 32 ), through which a composition of the intake air from recirculated exhaust gas and from fresh air ( 33 ), which have a suction area ( 25th ) is supplied, is adjustable.

In an intake passage ( 24 ) of the diesel engine ( 11 ) is preferred between the connection point of the exhaust gas recirculation device ( 30th ) and an engine inlet ( 26th ) a compressor ( 19th ) intended. The compressor ( 19th ) is preferred by the turbine ( 18th ) driven directly or indirectly.

According to a further aspect of the present invention, a synthetic diesel fuel that burns with little or no soot can be used as fuel. In particular in high-load operation (MODE 3), the diesel engine ( 11 ) are operated with an air-fuel ratio that is significantly lower than that of conventional diesel fuels, in particular in a range between 1.05 and 1.15. If dimethyl ether is used as the fuel, for example an air-fuel ratio of 1.05 be achieved. If oxymethylene ether is used as fuel, even lower values for the air / fuel mixture are possible. But diesel fuels can also be produced using the so-called GtL process (gas-to-liquid), which at least enable smoke-free or soot-free combustion at an air-fuel ratio of around 1.25. In the context of the present disclosure, one of the aforementioned fuels, a combination of the aforementioned fuels or a conventional diesel fuel can be used which is mixed with at least one of the aforementioned fuels. Alternatively or additionally, other suitable synthetic diesel fuels can be used alone or in combination with one of the aforementioned fuels.

Modifications of the invention are possible in various ways. In particular, all of the features written, shown or otherwise disclosed for the exemplary embodiments can be combined with one another or replaced with one another as desired.

The drive device ( 10 ) preferably comprises at least one nitrogen oxide sensor (NOx sensor 36 ) in the area of the exhaust passage, especially shortly or directly in front of the exhaust ( 16 ). Alternatively or additionally, another nitrogen oxide sensor can be installed downstream of the engine outlet ( 15th ) be arranged. On the basis of a determined nitrogen oxide content in the exhaust gas ( 34 ) at at least one point within the exhaust gas passage ( 14th ), especially downstream to the engine outlet ( 15th ) and upstream to the exhaust ( 16 ) a NOx conversion efficiency can preferably be determined. In the 3 in steps S11 and S12 As an alternative or in addition to a comparison of the exhaust gas temperature T_Ex against the first and second temperature threshold values (T1, T2), the specified tests can provide for a comparison of the actual conversion efficiency with a target value. A selection of the steps S30 and or S20 can also be dependent on the actual NOx conversion efficiency falling below a target efficiency.

List of reference symbols

10 Propulsion device / diesel hybrid propulsion Propulsion device / diesel hybrid drive 11 Diesel engine Diesel engine 12th Hybrid drive / electric motor Hybrid drive / electric motor 13 Exhaust aftertreatment device Exhaust gas after treatment device 14th Exhaust passage Exhaust gas passage 15th Engine exhaust Engine outlet 16 Exhaust Tail pipe 17/17 ' Fuel dispenser / fuel injector Fuel addition device / fuel injector 18th turbine turbine 19th compressor Compressor 20th Catalytic converter / three-way catalytic converter / LNT Catalyst / three-way catalyst / LNT 21st Oxidation catalyst and / or filter Oxidation catalyst and / or filter 22/22 ' Plasma generator Plasma generator 23 Control device Control device 24 Intake passage Intake passage 25th Suction area Intake section 26th Engine inlet Engine inlet 27 Combustion chamber Combustion chamber 28 Fuel injector Fuel inector 29 Accumulator / electrical driving energy storage Accumulator / electric propulsion energy storage 30th Exhaust gas recirculation Exhaust gas recirculation 31 Exhaust gas cooler Exhaust gas cooler 32 Control valve Control valve 33 Fresh air Fresh air 34 Exhaust gas Exhaust gas 35 Lambda sensor Lambda sensor 36 NOx sensor NOx sensor P * Target performance / target Target power / target Torque Torque Pd Power output Output power of diesel Diesel engine engine Pel Performance of the Power of electric Electric motor (recording engine (intake or o. delivery) output power) Pr Nominal value / nominal power Rated power for for continuous operation of the permanent operation of Diesel engine Diesel engine T_Ex Exhaust gas temperature Exhaust gas temperature T1 First temperature First temperature Threshold threshold T2 Second temperature Second temperature Threshold threshold Qi Injection quantity Fuel injection Fuel / burned quantity / burned fuel Fuel quantity quantity NE rotation speed Rotational speed

Claims (11)

Drive device for a vehicle with a diesel engine (11) and an electric motor (12), the drive device (10) comprising: - an exhaust gas aftertreatment device (13) for treating the exhaust gas (34) of the diesel engine (11), the exhaust gas - Aftertreatment device (13) has an exhaust gas passage (14) on which, in the flow direction of the exhaust gas (34), are arranged: ◯ A controllable fuel addition device (17) to add fuel to the exhaust gas (34) in the exhaust gas passage (14); ◯ A catalytic converter (20) for removing nitrogen oxides (NOx) from the exhaust gas (34) by reaction with the added fuel; - A control device (23) for controlling the addition of fuel; characterized in that the control device (23) is designed to - in high-load operation (MODE 1) of the drive device (10) to control the fuel adding device (17) in such a way that by adding fuel to the exhaust gas (34) (Post-engine addition amount) the air-fuel ratio of the exhaust gas (34) in the region of the catalytic converter (20) is approached to a target value which is close to the stoichiometric equilibrium; AND - to determine a required amount for a fuel addition in the diesel engine (11) (in-engine addition amount), which is required in addition to the after-engine addition amount to keep the air-fuel ratio of the exhaust gas (34) in the range of the catalytic converter (20) to approach the target value; AND - to generate an addition control instruction for the diesel engine (11) so that the in-engine addition amount of fuel is added to the drive device (10) in high-load operation (MODE 1); - To generate a compensation control instruction for the electric motor (12) so that an excess power (Pex) of the diesel engine (11), which results from the in-motor addition amount, is absorbed by the electric motor (34). Drive device according to Claim 1 , wherein the catalytic converter (20) is a three-way catalytic converter or a NOx storage catalytic converter. Drive device according to one of the Claims 1 or 2 , a plasma generator (22) being arranged upstream of the catalytic converter (20). Drive device according to one of the preceding claims, wherein the control device (23) is designed to generate the addition control instruction in such a way that it comprises a specification for the type of injection, so that the in-motor addition amount - is added completely as part of a main injection, OR - is added proportionately as part of a main injection and proportionately as part of a post-injection. Drive device according to one of the preceding claims, wherein the drive device (10) comprises an exhaust gas recirculation device (30) which recirculates exhaust gas (34) from the exhaust gas passage (14) to an intake passage (24) of the diesel engine (11), and wherein the exhaust gas recirculation device (30 ) in particular exclusively recirculates an exhaust gas (34) which is taken from the exhaust gas passage (14) at a point downstream to the catalytic converter (20) or further downstream after a fuel oxidation device (21), so that the content of free hydrocarbons that is released from the In-engine added amount and / or the post-engine added amount result, is reduced or eliminated in the recirculated exhaust gas. Drive device according to one of the preceding claims, wherein the fuel is a synthetic diesel fuel that burns with little or no soot, and wherein in particular in high-load operation (MODE 1) the diesel engine (11) is operated with an air-fuel ratio between 1.05 and 1.15. Operating method for a drive device (10) according to the preamble of Claim 1 , wherein the operating method comprises a high-load operating mode (MODE 1) in which the following steps are carried out: Adding fuel to the exhaust gas (34) downstream of the diesel engine (11) and upstream of the catalytic converter (20) (post-engine) Addition of fuel) in order to approximate the air-fuel ratio of the exhaust gas (34) in the region of the catalytic converter (20) to a desired value which is close to the stoichiometric equilibrium; - Determination of a required amount for a fuel addition in the diesel engine (11) (in-engine addition amount), which is required in addition to the post-engine addition amount to the air-fuel ratio of the exhaust gas (34) in the area of the catalytic converter (20) to approach the target value; - Adding the in-engine addition amount in the diesel engine (11) with any generation of excess engine power (Pex); - Taking up the excess engine power (Pex) of the diesel engine (12) on the electric motor (13). The operating method according to the preceding claim, wherein the operating method further comprises the following steps: - Determination of a target power or a target torque (P *); - If the exhaust gas temperature (T_Ex) exceeds an upper threshold value (T2): Limitation of the output power or the output torque (Pd) of the diesel engine (11) to a fixed nominal continuous operation value (Pr); AND - If no electrical drive support is possible, execute the high-load operating mode (MODE 1). Operating procedure according to one of the Claims 7 or 8th , further comprising: - If electrical drive assistance is possible: operating the diesel engine (11) so that it delivers power or torque (Pd) equal to or below the rated continuous operation value (Pr); AND if the output power or the output torque (Pd) is below the target power or the target torque (P *): Operation of the electric motor (12) to cover the power gap or the torque gap (P * -Pd). Operating procedure according to one of the Claims 7 to 9 , wherein the operating method further comprises the following steps: determining a target power or a target torque (P *); - If the exhaust gas temperature (T_Ex) falls below a lower threshold value (T1) and no electric charging is possible: Deactivate the diesel engine (11) so that the electric motor (12) produces the full setpoint power or the full setpoint torque (P *). Operating procedure according to one of the Claims 7 to 10 , wherein the operating method further comprises the following steps: determining a target power or a target torque (P *); - If the exhaust gas temperature (T_Ex) falls below a lower threshold value (T1) and electrical charging is possible: Operate the diesel engine (11) so that it generates an output or torque (Pd) above the target output or above the target torque ( P *) delivers and absorbs the excess power or the excess torque on the electric motor (12).

Images